Diffractive Optics and Spatial Light Modulators

Executive Summary

Light is thought to have a dual nature of both a wave and a particle, and this duality is crucial to understanding some aspects of light. Optical phenomena such as light propagation through optical elements - also known as light reflection or transmission - can be described by geometrical optics and illustrated by various ray tracing techniques. This description is phenomenological only and does not require knowledge of any fundamental physical constants or any specific physical phenomena. An optical element is a piece of equipment with a single optical function. Most of the currently used optical elements, such as lenses, optical filters, prisms, mirrors, as well as their various combinations, which can be found in optical instruments and devices, bend incoming light rays by refraction or transmission depending on their shape and their refractive index.

However, there are other optical phenomena such as diffraction and interference of light, for example, that cannot be explained by the ray tracing method since their origin depends on the physical nature of light; but it can be explained by physical optics. Optical elements that operate on the principles of diffraction to control the wavefront - specifically, its phase and amplitude - are referred to as diffractive optical elements (DOEs). Diffractive optical element is a generic term that includes various optical elements such as: Fresnel lens, Fresnel zone plates, holographic optical elements, elements based on binary optics, diffraction gratings, as well as other diffractive optical elements, namely, surface-relief diffractive lenses, collimators, filters, holographic optical elements (HOE) and computer-generated holograms.